The invention relates to a push-down hydraulic well drilling motor with axial flow. The attached drill is rotated by the motor through torque generated by the energy of the flowing flush water.
The rotary-swivel heads and so-called push-down drilling motors used for the drilling of hydrocarbon wells are generally known equipment.
The drilling turbine is regarded as conventional equipment, the r.p.m., torque and efficiency--as in any machine functioning on the fluid mechanical principle--depend on the flow of liquid and load.
A drawback of the drilling turbine is that overloads cause it to stop, it is sensitive to impurities in the water and has a relatively short life-span. Also putting the unit into service and starting it are complicated.
In the electrical push-down drilling motors the insulation deteriorates due to the heat and pressure conditions prevailing in the bore hole causing difficulties. The appropriate r.p.m. can be ensured generally only with gear transmission. Use of the electric push-down drilling motor is inhibited, or limited also by the cable connection. Another known drilling motor is the holing-type which functions on the principle of volumetric displacement. It consists of an internally threaded stator of multiple arch section (multiplex thread) and an externally threaded rotor, in which the thread number is different from that of the stator.
All of these generally known push-down hydraulic drilling motors have a problem caused by the placement of the shaft of the rotor in the center of gravity not in the centerline of the jacket. The centerline (median) of the rotor thus moves in a circular orbit around the centerline of the jacket and stator. Consequently the rotary motion of the rotor only can be transmitted to the drill, or to the transmitting driving shaft through the propeller shaft. The propeller shaft is at an angle to the rotor or driving shaft, thus the radial component-due to the obliquity of the propeller shaft-of the reaction force arising from the hydraulic pressure and acting on the rotor, increases the friction between the stator and rotor, thereby considerably reducing the efficiency and life-span of the drilling motor. The propeller mechanism can be built into the drilling motor of fixed length only at the expense of the useful motor-part producing the torque. The useful cross section for transmitting the energy carrier medium for the torque can be only a small proportion of the cross section of the device. Due to the excentricity of the median of the rotor, significant mass forces arise at higher r.p.m., deterimentally loading the stator and rotor surfaces, causing vibration and leading to breakage due to fatigue of the drill pipe. The increased friction force reduces also the torque utilizable for drilling.
In addition to well known drilling motors which attempt to overcome the problems mentioned, there is also a unit in which the rotor (spindle) suitable for rotation of the drilling tool revolves around the shaft in its center of gravity eliminating vibration, yet it is not centered with the jacket. Gears are used to synchronize, or transmit the rotary motions, however, because of space requirements these devices are unsuitable for drilling. Thus, there is still a need for a drill in which there is transmission of the rotation of the rotary stator, the so-called rotary chamber member, or spindle into the centerline of the external jacket and maintenance of the flush flow necessary even in case of jamming.